CHICAGO (STMW) — A Southwest Side man already being held in Cook County Jail was charged Wednesday in the 2010 murder of three people found dead inside a car.

Roberto Cerda, 24, of the 5600 block of South Trumbull Avenue, was charged with first-degree murder for the deaths of three men found in a vehicle in the 4800 block of South Whipple Street on May 18, 2010, sources said.

Cerda is allegedly part of a group police suspect killed as many as 12 people in drug-related murders throughout the city, sources said.

Cerda was booked into the Cook County Jail on May 19 on an unrelated charge and is being held on $50,000 bond, according to the Cook County Sheriff’s website.

The bodies of three men were found about 7 a.m. May 19, 2010, in the back seat and trunk of a car parked in an industrial area in the 4800 block of South Whipple Street, police said. The Cook County Medical Examiner’s office identified the men as 37-year-old Andres Butron, of the 2800 block of S. Christiana Ave., 42-year-old Ernesto Alquien, of the 2200 block of N. Meade Ave., and 28-year-old Hector Romero, of the 1600 block of N. Karlov Ave.

Autopsies determined Alquien and Romero died of multiple gunshot wounds and their deaths were ruled homicides, the medical examiner’s office said. Autopsy results for Butron were not immediately available.

In February, Chicago Police said Arturo Ibarra, Raul Segura-Rodriguez and Augustin Toscano were part of a group suspected in as many as 12 drug-related murders — including the May 18, 2010, triple homicide in which Cerda is now charged. He has not been charged in any of the other murders.

Ibarra, 37, was shot by officers Feb. 26 after police said he entered a home in the 5800 block of North Winthrop Avenue with Segura-Rodriguez and Toscano and bound the hands of three people with belts and cut their throats. Police shot Ibarra during a chase through the North Side.

Segura-Rodriguez, 36, was charged with two counts of first-degree murder for those killings. He has also been charged with killing four people Sept. 2, 2010, in a garage in the 6100 block of South Kildare Avenue, prosecutors said. He is being held without bond.

Toscano has only been charged in the murders in the 5800 block of North Winthrop Avenue. He is also being held without bond.

At least some of the men are also suspects in the April 2010 triple murder in the 2300 block of West 36th Street, where three other men were found bound in a car.

Chicago Police detectives are still investigating all the shootings, police said.